Device for discharging cellulosic pulp out of a container

ABSTRACT

A device for discharging pulp through a centre outlet at the bottom of a container comprises three or more rotary scrapers located eccentrically of the outlet and being distributed over the half-spherical bottom of the container. Radial scraper arms attached to inclined shafts are swung forth and back in order to sweep over separate areas of the container bottom and advance the pulp towards the outlet.

United States Patent Richter Apr. 16, 1974 1 DEVICE FOR DISCHARGING CELLULOSIC 3,345,043 10/1967 Bovagne 259/102 PULP OUT OF A CONTAINER 872,729 12/1967 Hiller 2,402,521 6/1946 Woolley [75] Inventor: Johan C- F- C- Richter, St. Je p 3,134,576 5/1964 Lodige et a1 259/41 x Ferrat, France [73] Assignee: Kamyr Aktieholag, Karlstad, Primary ExaminerRobert B. Reeves Sweden Assistant ExaminerDavid A. Scherbel 22] Filed: Apr. 18, 1972 4 11957?! 4397'. FV ,"V, r P P? 7,

Cushman [21] Appl. No.: 245,167

Related US. Application Data ABSTRACT [63] Continuation of Ser. No. 20,759, March 18, 1970,

abandoned- A device for discharging pulp through a centre outlet at the bottom of a container comprises three or more [52] US. Cl. 222/271, 259/41 rotary scrapers located eccentrically ()f the outlet and [51] Int. Cl B011 15/02 b ing di tribut d over the half-spherical bottom of the 35E53:-wZZ /QZQ J container. Radial scraper arms attached to inclined 2227 1 103, shafts are swung forth and back in order to sweep over U m W7 V W I W separate areas of the container bottom and advance I 56] References Cited the pulp towards the outlet.

UNITED STATES PATENTS 1 Claim 2 Drawing Figures 2,616,340 11/1952 Knoll 259/103 X APR IEO

WEN

& E33 95 DEVICE FOR DISCHARGING CELLULOSIC PULP OUT OF A CONTAINER This is a continuation of application Ser. No. 20,759 filed Mar. l8, 1970 now abandoned.

The invention relates to a device for discharging cellulosic pulp through a bottom centre outlet of a container. Said container may be, for instance, a cellulosic digester, a washing apparatus or a bleaching tower, and may be adapted for discharging the pulp either continuously or batchwise.

In order to prevent clogging of the outlet and also for getting a uniform descending motion of the pulp over the entire cross-section of the container, such containers are usually provided with a bottom scraper rotary about a central vertical axis and having arms extending radially so far as to sweep over the greater part of the bottom of the container, thereby forwarding the pulp to the outlet at the centre of the bottom.

The invention has for its object to provide a pulp discharging device suitable for use when the space close to the centre of the container bottom is occupied for other purposes. e.g., for the insertion ofa vertical fluid inlet or outlet tube, or for bearings of such a tube, or for a shaft carrying spaced platforms, stirring arms or similar.

The device of the invention comprises three or more scraper means situated around the outlet and each rotary about an axis directed radially inwards and obliquely upwards. Said scraper means are arranged in common to sweep over the greater part of the container bottom in order to forward the pulp down into the central outlet, the hubs of said scraper means being placed at a distance from said outlet, so that the centre part of the container bottom can be designed out of consideration to other factors and without regard to the scraper device.

The invention will be more closely described herein below with reference to the accompanying drawing, in which FIG. 1 is a vertical sectional view ofa container equipped with the scraper device according to the invention, and FIG. 2 is a cross-sectional view of a detail taken along the line llll in FIG. I.

The drawing shows the lower end of an upright container with a cylindrical wall I1 and a half-spherical bottom 13. In the centre of the bottom, an outlet is formed as a depression bounded by a cylindrical wall 15 having a lateral tubular extension 17 to which a conduit can be connected. A cellulosic fibre material to be treated in the container is supplied, preferably continuously, to the top of the container. Said material may consist of cellulosic pulp. e.g., high-consistency pulp having a dry content of 8 to percent. and the treatment performed in the container may be bleaching of the pulp by means of a bleaching agent of any kind.

Along the vertical axis of the container there extends a shaft 19 which may take the shape ofa tube and serve for the supply of bleaching agents, washing liquor, etc. and which may have stirring arms or similar connected to it. The lower end of the shaft 19 extends centrally through the depression of the container bottom and is sealed thereto by means of a stuffing box 21. On the outside said shaft carries a toothed disc 23 menat to be connected by means of a chain to a driving means for rotating the shaft 19.

The above-described container is provided with a discharging device designed according to the invention and consisting of four equal movable scraper means, only three 25, 27, 29 being shown in the drawing.

The scraper means 25 consists of a hub 31 and scraper arms 33 extending radially therefrom. The hub is fastened to a shaft 35 which extends through a stuffing box 37 in the container bottom and is connected to a motor 39 attached to a bracket 41 on the outside of the container bottom. The motor 39 may be arranged either to rotate the scraper means 25 or to turn them back and forth through an angle of about l. In the latter case the motor may consist of a hydraulic servomotor or possibly a reversible electric motor. The shaft 35 is inclined at an angle of 40 to 50 to the vertical and coincides with a radius of the spherical curvature of the bottom. The length of the scraper arms 33 is preferably equal to V2 or Vs of the radius of the curvature of the container bottom or of the radius of the adjoining cylindrical part 11 of the container. The arms 33 which are straight and of a cross-section tapering towards their free ends, are set at an angle to the shaft 35 somewhat less than As an alternative, they may be slightly curved in order to follow the spherical wall more closely. In one direction their utmost ends reach forth almost to the cylindrical shell part 11 and in the other direction almost to the edge of the cylindrical depression 15. Thus, each scraper sweeps over a calotteshaped part of the container bottom located eccentrically to the outlet. All scraper means are situated symmetrically around the outlet and their ranges of operation, which almost interfere, cover the greater part of the spherical bottom zone. If desired, merely three scraper means may be used, the covered region then being smaller, or more than four scrapers may be used. Furthermore, it is possible to have the ranges of operation overlap, in which case the movements of the scraper arms must be synchronized in such a manner as not to interfere.

In the embodiment shown in the drawing, each scraper means is provided with two opposite scraper arms extending diametrically from the hub 31. Preferably, the shaft 35 is driven so as to swing the scraper arm through an angle of about in one direction to an end position in which the arm is positioned essentially in a vertical plane, and then swing the arm through an equal angle in the opposite direction back to the initial position; said movement being repeated continuously. The scraper arm may be designed with a triangular cross-section as shown in FIG. 2, the side 43 thereof facing the container wall, the side 45 being approximately perpendicular thereto, and the side 47 facing inwardly and forming an angle to the container wall. The side face 45 effectively moves the pulp when the scraper arm is swung with said side face leading in the motion, whereas the pulp is merely pushed aside by the inclined side face 47 when the latter leads in the motion. Therefore, when the lower scraper arm 33 is swung upwardly from the shown lower end position, the same easily slides past the pulp, but when the scraper arm swings down again from the upper end position, the transverse side face 45 is active and feeds the pulp downwardly towards the outlet 15. A suitable rate of swinging the scraper arms may be 5 to 30 cycles per minute.

Of course. each scraper device may comprise more than two scraper arms, and the arms may be curved in the longitudinal direction in order to move the pulp more easily when swung in one direction than in the other. If desired, the arms may be replaced by the shovels kept rotating in one direction only.

Approximately at the level of the scraper means the shaft 19 is provided with a conical portion 49 widening in the downward direction and terminated by a plane annular face 51. The maximum diameter of said conical portion is approximately equal to the diameter of the cylindrical depression in the container bottom. In this manner a narrow passage is formed at the lower part of the ranges of operation of the scraper means. When the pulp has been fed through said narrow passage by means of the scraper means, its continued motion to the outlet 15, 17 is facilitated due to the widening of the passage. The discharge of the pulp may also be assisted by supplying flushing liquid through spray nozzles inserted in the bottom of the container.

What is claimed is:

1. Apparatus comprising a generally cylindrical treating vessel terminating with an essentially hemispherical bottom portion including a discharge outlet positioned centrally therein, at least three scraper means mounted in said bottom portion and distributed around the outlet, each of said scraper means being rotatable about an axis directed radially inwards and obliquely upwards with the axes of said means positioned symmetrically about the outlet and forming an angle of 40 to 50 to the vertical, each of said scraper means being arranged to sweep over a calotte-shaped part of the vessel bottom lying eccentrically to the outlet, a drive shaft extending through the bottom portion of said cylinder to support each of said scraper means and separate means operatively associated with each of said shafts for driving said scraper means, said scraper means comprising substantially straight scraper arms extending radially from the inner end of each shaft, at least two diametrically directed scraper arms being located on each driving shaft and said arms having a length equal to /2 to /a and of the radius of the adjoining cylindrical part of the said vessel, said scraper arms being positioned close to said hemi-spherical bottom portion so as to sweep said bottom portion and forward material which is resting on said bottom portion downwards and inwardly towards said discharge outlet as said arms sweep over said bottom portion, and wherein said outlet is formed by a circular depression in the bottom of said vessel and said vessel includes a vertical shaft extending through the vessel bottom, said vertical shaft approximately at the level of the scraper means being provided with a widened portion, the maximum diameter of which is approximately equal to the diameter of said depression. l

UNITED STATES PATENT oTTTcE V CERTWECATE M QQRREQTWN Dated April 116, 1.974

Patent No. 3 804 304 Inventor(s) Johan C.F.C' Richter It is certified that error appears in the above-identified patent; and that said Letters Patent are hereby corrected as shown below:

In the heading, add --Foreign Application Priority Data April 8, 1969 Sweden 4888/69- Column 4, line 12, "and" should be deleted after "1/3".

Signed and sealed this 5th day of November 1974.

(SEAL) Attest:

McCOY M. GIBSON JR, Co MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-105O (10- USCOMM DC 60376 P69 a U 5, GOVENNMENY PRINIING OFFICE I969 O-366'J.N 

1. Apparatus comprising a generally cylindrical treating vessel terminating with an essentially hemispherical bottom portion including a discharge outlet positioned centrally therein, at least three scraper means mounted in said bottom portion and distributed around the outlet, each of said scraper means being rotatable about an axis directed radially inwards and obliquely upwards with the axes of said means positioned symmetrically about the outlet and forming an angle of 40* to 50* to the vertical, each of said scraper means being arranged to sweep over a calotte-shaped part of the vessel bottom lying eccentrically to the outlet, a drive shaft extending through the bottom portion of said cylinder to support each of said scraper means and separate means operatively associated with each of said shafts for driving said scraper means, said scraper means comprising substantially straight scraper arms extending radially from the inner end of each shaft, at least two diametrically directed scraper arms being located on each driving shaft and said arms having a length equal to 1/2 to 1/3 and of the radius of the adjoining cylindrical part of the said vessel, said scraper arms being positioned close to said hemi-spherical bottom portion so as to sweep said bottom portion and forward material which is resting on said bottom portion downwards and inwardly towards said discharge outlet as said arms sweep over said bottom portion, and wherein said outlet is formed by a circular depression in the bottom of said vessel and said vessel includes a vertical shaft extending through the vessel bottom, said vertical shaft approximately at the level of the scraper means being provided with a widened portion, the maximum diameter of which is approximately equal to the diameter of said depression. 